Metal working method and lubricant therefor



United States Patent O lVIETAL WORKING METHOD AND 1 LUBRICANT THEREFOR Otto Turinsky, Western Spring, Ill., assignor to Armour and Company, Chicago, IL, a corporation of Illinois No Drawing. Application April 12, 1951 Serial No. 220,707

6 Claims. (Cl. 205-2) My invention relates to the working of metals, and particularly to the steps of applying a film of corrosioninhibiting surface active lubricant to the surface of ferrous and non-ferrous metals and forming these metals by cutting, grinding or drawing methods.

An object of my invention is the provision of an economical method for cutting and drawing metals in a uniformly smooth manner without producing uneven surfaces and without causing a ripping effect.

Another object of my invention is the provision of a method of forming metals by the use of corrosion-inhibiting surface active lubricants.

Other objects of my invention specification proceeds.

Many metal working operations such as drawing, grinding, cutting, etc. involve the common principle of contacting the surface of a metal part with a shaping tool or element so as to change the conformation or surface characteristics of the metal part. When such operations are carried out without the aid of lubricants, an undesirable amount of heat and friction is generated at the points of contact and a welding or binding effect is noted. Unless this heat can be dissipated, damage results to both the tool and the metal part, and in the case of poorly lubricated deep-drawing and pressure stamping there is the additional danger of fracturing the metal part. 7

It is well known that non-surface-active lubricants such as mineral oil are unsatisfactory for many metal working operations, especially the drawing of metals. Such lubricants have. a tendency to flow away from the precise area 'in which the heat and pressure are greatest and where lubrication is most effective in preventing binding.

Emulsions of soap. and. fatin water have beenused as cutting and drawing compounds. The degree of success attained with these compounds is due to the fact that soap, being surface active, adheres to the surface of the metal being processed as well as the surface of the shaping tool. Likewise soap has an affinity for fat which is thus held upon the surface of the metal in a lubricative film. However, fat and soap are unavoidably caustic in nature and as a result of their use the metal surface is soon corroded.

In general, a surface active compound is composed of a combination of a water-soluble or hydrophilic chemical group and an oil-soluble or hydrophobic chemical. If such a compound does not ionize, it is said to be nonionic, while if it does ionize it is said to ionic. When that part of the ionized molecule containing the oilsoluble portion is the positive ion, or cation, the compound is said to be cation-active or cationic. Those ionic compounds such as soap having an oil-soluble anion are known as anionic agents.

I have discovered that instead of using a soap-fat emulsion as a metal working lubricant I can use cationic will be apparent as this tertiary amines to obtain excellent drawing and cutting characteristics while at the same time inhibiting corrosion of the metals.

ICE

Tertiary amines suitable for my process have the general formula (0 H2 0 Hi 0) zIE1 0 H2 C H: O) ,H

where R is a long chain aliphatic hydrocarbon radical having 12 to 20 carbon atoms and Where x and y are int'egral numbers from 1 to 49. For example, the long chain aliphatic radical R may be dodecyl, hexadecyl, eicosyl, octadecenyl, or octadecynyl. prefer to use N,N'-bis(2-hydroxy-ethyl) soya amine in which the soya radical comprises a mixture of saturated and unsaturated radicals including hexadecyl, octadecyl, octadecenyl, octadecynyl, and eicosyl. The number of ethenoxy groups as indicatedby x and y may be varied. Thus, for five ethenoxy groups x and y maybe 1 and 4 respectively or 2 and 3 respectively. Y may be greater than x, and the sum of x plus y may be as large as 50. In general, the water solubility of these hydroxylated tertiary amines is increased by the addition of ethenoxy groups. ethyl) aliphatic amines and their acid salts.

Although some of these hydroxylated tertiaryamines as well as the hydroxylated tertiary amine acid salts are relatively insoluble in water, they may be employed in the form of an emulsion or saturated solution. For example, they may be used advantageously in a water emulsion in the ratio of one part of amine to 3 parts of water.

These amine compounds may be advantageously used in their water-soluble salt form, .The amine salt is? formed bycontacting the amine with'an acid. Whileithe: amine salts of strong acids may be used, I prefer 'to use. I usephosphoric acid? the amine salts of weak acids.

with considerable advantage and in particular orthophds- .phoric acid. Some of the amine acid salts such as phos-- phoric and lactic are effective in inhibiting corrosion...

, These hydroxylated tertiary amine salts are stable in: aqueous solution below a pH of approximately 8. I: have found that solutions of these salts are more effective: as corrosion inhibitors above pH 5. Because of'tli'ese.

limitations I prefer-to practice my process using as a lubricant the acid salt of the amine in aqueous solution having a pH between about Sand about 8.

The use of a solution of the hydroxylated tertiary amine salt of a weak acid is desirable forthe reason that.- such asolution actsasa bufier'and resists ;,any change;

of orthophosphoric acid sufficient to completely dissolve the amine in Water. The pH of such a solution is approximately 7, and if desired the pH may be lowered by adding more phosphoric acid. The drawing bath is then made up by dissolving one part of this amine formulation in about forty parts of water.

In either a cutting or drawing operation, the surface of the metal to be formed may be immersed in an amine bath before passing to the forming elements such as drawing dies or cutting tools. If the metal stock cannot be conveniently immersed in the bath, the amine solution may be sprayed or poured on the metal surface be- Patented Dec. 15, 19 5913:

For my process I In my process I preferably use bis-(2-hydroxyforeeit is subjected .to the forming step. Depending upon conditionscencountered, theamine lubricantmay be .ap-

plied to the metal surface in .dry form or in the form of a paste or solution. The method of applying the lubricant iss'not limited tozimmersiornof the;metal part;,or spraying or pouring. In general any IIIOihOdLOfLfiPPliCZ: tion is suitable which results incontacting the lubricant at the interface between the metal surface and the metal working tool. Before passing to the metal working step a Wet metal surface may. first be allowed to dry without appreciably. impairing the lubricative qualities. After-the metal stock has been coated with a film of the amine lubricant, it may be processed with at leastone forming tool-before it.is necessary to re-treat the surface with more lubricant. sive .forming operations can be carriedout without intermediate lubrication.

My process is not limitedto the drawing or cutting of metals. In general, it may be practiced. in any operation involving lubrication of the interface between a metal surface. and a metal-working tool.

Other modifications of the process all Within the spirit of? my. invention will readily occur to those skilled in the-art.

Iclaim:

1. In. the art of working metal by cutting, grinding,

drawing, and the like, the step which comprises carrying out the process with the portions of themetal being worked in contact with a material selected from'the group consisting of hydroxylated tertiary aminesand the acid salts. thereof, said amines having the general formula (CH2CH20).-.H 'RN I (CHZCH),H wherein Rv is a straight chain aliphatic hydrocarbon radical. having 12 to.2O carbon atoms and x and y are integral numbers, the sum of x and y being in the range from about 2 to 50.

2. In the art of working metal by cutting, grinding, drawing, and the like, the step which comprises. carrying out. theprocess with the portions of the metal being worked in contact With an aqueous solution containing approximately 3 parts by weight of water per part of an acid salt of a hydroxylated tertiary. amine, said amine having the formula wherein'R is a straight chain aliphatic hydrocarbonradical having 12 to 20 carbon atoms and x and y are integral In some cases as many as three succes-- 4 numbers, the sum of x and y being in the range from about-2 to .50..

3. In the art of working metal by cutting, grinding,

from about 2 to 50.

4. A process according to claim 3 wherein thepHof said aqueous solution is in, the range offrom about 5.

to about8.

5., In a process, for the drawing of metal, the stepwhich comprises carrying out the process with the portlons of the metal being drawn in contact with an aqueous solution containing approximately 3 parts by weight of water per part of the phosphoric acid salt of;

a hydroxylated tertiary amine having the formula (CH2CH20)=H (CILOHnO) ,H

wherein R is arstraight chain aliphatic hydrocarbonradical having 12 to 20 carbon atoms-and x and y are integral numbers, the sum of x and y being in the range tron;- about 2m 50. i

6. A process accordingto claim 1 wherein an acids alt of N soya bis(2 hydroxypolyethoxyethyl) amine is employed;

References Cited in the file of this patent V UNITED STATES PATENTS 1,991,395 Kocoor Oct. 24, 1932 2,223,037 Ihrig Nov. 26, 19.40. 2,231,228 Singer Feb. 11, 194.1 2,233,383 DeGroote Feb. 25, 1941 2,275,198 Patnode Mar. 3, .1942 2,297,221 Huttenlocher Sept. 29, 19.42 2,298,636 Prutton Oct. 13, 1942 2,298,640, Prutton Oct. 13; 1942 2,474,325 Rodgerset al June 28, 1949.- 2,541,678 Swanay Feb. 13, 1951 

1. IN THE ART OF WORKING METAL BY CUTTING, GRINDING, DRAWING, AND THE LIKE, THE STEP WHICH COMPRISES CARRYING OUT THE PROCESS WITH THE PORTIONS OF THE METAL BEING WORKED IN CONTACT WITH A MATERIAL SELECTED FROM THE GROUP CONSISTING OF HYDROXYLATED TERITARY AMINES AND THE ACID SALTS THEREOF, SAID AMINES HAVING THE GENERAL FORMULA 